U.S. Pat. No. 5,331,500 describes a circuit-breaker. A data storage device which is described therein is an interface card which is fixedly secured to the support of a circuit-breaker in such a way that an operative connection with the tripping device is not established until the tripping device is inserted into the circuit-breaker. Signals from the current transformer are sent to the tripping device through lines connecting the current transformer to the interface card. The tripping device thus receives information about the characteristics of the circuit-breaker.
Due to the fact that the data storage device is a fixed component of the circuit-breaker and the characteristic values are stored in the tripping device itself, this reliably achieves the result, in comparison with another conventional method, that invariable features of the circuit-breaker such as the type and rated current as well as the characteristics of the current transformers which are also permanently installed in the circuit-breaker are invariably taken into account even when the electronic tripping device is replaced. However, this means that when a fault occurs and the electronic tripping device is subsequently tested, such faults which have occurred in the data storage device are not detected. Furthermore, greater caution is required when the current transformers of the circuit-breakers are to be replaced and therefore the data storage device must also be adjusted or replaced.